Globally, about 248 million people are chronic HBV surface antigen carriers, and about 5% of them also had hepatitis delta virus (HDV) infection as well. The prevalence of HBsAg in Egypt is intermediate (2-7%) .

Hepatitis D virus (HDV) is an incomplete RNA virus that needs hepatitis B surface antigen (HBsAg) to help its replication. HDV is considered a subviral particle because it depends on HBV for its propagation. Combined HDV- HBV infection produces more severe liver affection than HBV alone.

HDV infection leads to both of acute and chronic liver illnesses. Acute HDV infection can occur at the same time with acute HBV infection (coinfection) or can be superimposed on the top of chronic HBV infection. About 20% to 30% of coinfections of HDV and HBV in humans develop fatal fulminant hepatitis versus 2% of patients with acute hepatitis B mono-infection. Worldwide, Hepatitis D virus (HDV) infection present in more than 15 million people and it is endemic in the Middle East . In Upper Egypt, data about the prevalence, clinical, laboratory and virological characters of Hepatitis D virus-infected patients is rare.

This study aims were:

1. To estimate the prevalence of hepatitis D virus infection among HBsAg positive individuals.
2. To determine the clinical, laboratory and virological characters of HDV infected patients.

Inclusion Criteria:

• HBV related liver disorder, aged 18-60 years.
• HBsAg positive individuals were divided into different clinical categories according to EASL 2012 and we revised this classification according to EASL 2017. HBeAg negative chronic infection; HBeAg positive chronic infection), Acute hepatitis, Fulminant hepatitis, Chronic hepatitis (HBeAg positive and HBeAg negative), Liver cirrhosis, and Primary HCC.

Exclusion Criteria:

• Dual infection with other viruses as HCV and/or HIV, auto-immune or alcoholic hepatitis.

This study was a hospital-based, prospective, cross-sectional analytic one. The study was carried out on 186 HBsAg positive cases who were recruited from Tropical Medicine and Gastroenterology Department, Al Rajhi Liver Hospital, Assiut University, and Sohag University Hospital during two years.The Participants accepted to participate in the study.